A conventional cutter 10 for making wooden dowels, plugs, or tenons is shown in FIGS. 1A and 1B and comprises a shank 12 to be received within a drill press chuck and a body portion 14. The body portion 14 includes a cutting tooth 15 having a leading arris 16 which contacts and cuts the wood as the cutter 10 is rotated and lowered into the wood by the drill press. The cutting tooth 15 is also defined by an interior surface 25 and by an exterior surface 11. The body portion 14 of the cutter 1 0 further includes a beveled surface 19 on an exterior of the cutter 10 and a ridge 20 formed at a juncture of the beveled surface 19 with the interior surface 25 of the cutter 10. A flute 18 is defined between the cutting tooth 15 and the beveled surface 19 of the cutter 10.
In operation, the cutter 10 is secured within the chuck of a drill press and is rotated at a relatively high speed (the appropriate speed depends on the diameter of cutter 10). As the cutter 10 is being lowered by the drill press, the ridge 20 forms a circular depression in a piece of wood and is the first part of the cutter 10 that contacts the wood. After the depression is formed by the ridge 20 and the cutter 10 is lowered an additional distance, the leading arris 16 of the cutting tooth 15 next contacts the wood and cuts a circular trough within the wood. As the cutter 10 continues to be lowered by the drill press, the ridge 20 and the cutting tooth 15 form a deeper trough in the wood, and a cylindrical wood member is received within a bore 29 of the cutter 10. The initial depression formed by the ridge 20 receives the interior surface 25 of the cutting tooth 15 thereby guiding and stabilizing the cutter 10 as it is lowered into the wood. The circular trough cut by the cutter 10 has an outer diameter defined by the exterior surface 11 of cutting tooth 15 and an inner diameter defined by the interior surface 25. The wood member received within the central bore 29 may be used as a dowel, tenon, or plug in ways apparent to those skilled in the art.
A problem with prior art cutter 10 is that a relatively large amount of frictional force is present between the cutter 10 and the wood. During operation, the ridge 20 of the cutter 10 is in continuous contact with the wood as the cutter 10 is being lowered into the wood. Also, in addition to the ridge 20, both the interior surface 25 and exterior surfaces 11 of cutting tooth 15 are in continuous contact with the wood since these surfaces 25 and 11 are respectively at the smallest and largest radial distances from a center C of the cutter 10. The inner surface 25 of the cutter 10 and an outer surface 21 formed above the beveled surface 19 are also formed at the smallest and largest radial distances of the cutter 10, respectively, so that both of these surfaces 25 and 21 are in continuous contact with the wood. Thus, in all, the ridge 20 and each of the surfaces 11, 21, and 25 are always in frictional engagement with the wood.
The other surfaces of the body portion 14 also come in contact with the wood during operation of the cutter 10 but to a lesser degree than the ridge 20 and surfaces 11, 21, and 25. These other surfaces of the cutter 10 include a second exterior surface 22 and a second interior surface 26 which are recessed relative to the outer surface 21 and the inner surface 25, respectively. Since the surfaces 22 and 26 are recessed relative to surfaces 21 and 25, respectively, the surfaces 22 and 26 are spaced farther away from the wood than surfaces 21 and 25 and thus have less contact with the wood. Even though these surfaces 22 and 26 are spaced apart from the wood, the surfaces 22 and 26 may nonetheless still contact the wood due to such factors as rotation of the cutter 10 at a slight angle offset from the vertical axis.
Each of the surfaces that are in frictional engagement with the wood generate heat when cutter rotates. Thus, during the rotation of the cutter 10, heat will be generated at the ridge 20 and along surfaces 11, 21, and 25. At times, sufficient heat will be generated to burn the surface of the wood and harmfully heat the cutter 10. The generation of harmful heat is especially problematic with hardwoods. Friction between the wood and the ridge 20 and surfaces 11, 21 and 25 also decreases the efficiency of the cutting operation. In order to cut the wood, the drill press must provide a rotational force greater than the frictional forces before the cutter 10 will even begin to rotate. The rotational force exerted simply to overcome the frictional forces increases the amount of torque that the drill press must be capable of providing.